Interpretive Summary: We examined the effectiveness of short bouts of low intensity walking following meals. Participants were elderly men and women at risk for glucose intolerance. All walking was on a treadmill at a comfortable pace for either 15 min following each meal or once per day for 45 minutes at either 10:30 am or 4:30 pm. Blood sugar levels were continuously monitored with a wearable device and the source (fat or carbohydrate) and amount of calories burned were determined. We found glucose control was much better with the three short duration exercises following each meal than either of the longer bouts of exercise or no exercise. This work has important clinical implications for the recommendations of exercise for elderly individual who are facing the possibility of impaired glucose control. These results are of interest to health care providers who are involved in making recommendations to the elderly to reduce risk for diabetes.

Technical Abstract:
The purpose of this study was to compare the effectiveness of three 15-min bouts of postmeal walking with 45 min of sustained walking on 24-h glycemic control in older persons at risk for glucose intolerance. Inactive older (=60 years of age) participants (N = 10) were recruited from the community and were nonsmoking, with a BMI <35 kg m-2 and a fasting blood glucose concentration between 105 and 125 mg dL-1. Participants completed three randomly ordered exercise protocols spaced 4 weeks apart. Each protocol comprised a 48-h stay in a whole-room calorimeter, with the first day serving as the control day. On the second day, participants engaged in either 1) postmeal walking for 15 min or 45 min of sustained walking performed at 2) 10:30 a.m. or 3) 4:30 p.m.. All walking was on a treadmill at an absolute intensity of 3 METs. Interstitial glucose concentrations were determined over 48 h with a continuous glucose monitor. Substrate utilization was measured continuously by respiratory exchange (VCO2/VO2). Both sustained morning walking (127 ± 23 vs. 118 ± 14 mg dL-1) and postmeal walking (129 ± 24 vs. 116 ± 13 mg dL-1) significantly improved 24-h glycemic control relative to the control day (P < 0.05). Moreover, postmeal walking was significantly (P < 0.01) more effective than 45 min of sustained morning or afternoon walking in lowering 3-h postdinner glucose between the control and experimental day. Short, intermittent bouts of postmeal walking appear to be an effective way to control postprandial hyperglycemia in older people.